I think there is one there, I can't remember which one it is. We rented from Enterprise and they picked us up fromt the hotel and drove us back after, it worked out great.
Downtown Disney location is for Alamo. I think all the big rental companies ave a location in the disneyland-harbor area. We rented from Budget at the airport, went to legoland the first day and dropped off the next day. Their location is close to the convention center. They also drove us back to Hojo. Its nice if you only need a car for a day or two.